pullmatic system double effect/empty

[New Rider]

Good morning to all,

Currently, in my application, I have a system of ''ammortizzzione'' consisting of a cylinder and a stem (like fork motorcycle). at the base of the cylinder a pressure of about 1/1.5 bar is applied. This pressure moves forward the stem which, once reached its position (maximum output), maintains it and at the same time in case of force against this pressure it acts as a shock absorber. to retract the draining shaft and manually retraggo. Good. At this point I don't want to let it go manually but I want it to automatically retract.
I could create a double effect cylinder but, given that the cylinders are of our production (they are not as iso cylinders)
I thought I'd use the vacuum technique. at the moment I have the need to make all the active stem the vacuum system so that the stem comes back everything.
Surely I will have said some chestnuts given my unknowledge of the empty sector.
you have any ideas or links to recommend.
I checked on the vacuum site but we always talk about pick and place motimentations and what else.
Thank you.

 

[meccanicamg]

I would say that the vacuum generates it or via a special compressor or through venturi.
sure it is easier to make positive pressure than negative though the maximum line works. it would be much cheaper to turn it into double effect rather than to invent unnecessary expensive things.

 

[meccanicamg]

I see it difficult for you to make a damp but you made a tire spring. It's all another thing....

 

[New Rider]

I see it difficult for you to make a damp but you made a tire spring. It's all another thing....

Save mechanical mg, as you rightly specified, the operation is comparable to that of the spring. I believe that pneumatic spring is the right term since I have no chance to adjust preload/return. You mean that?

I would say that the vacuum generates it or via a special compressor or through venturi.
sure it is easier to make positive pressure than negative though the maximum line works. it would be much cheaper to turn it into double effect rather than to invent unnecessary expensive things.

creating the double effect, as you say, would be much simpler but I should go to replace the shirts, create a double room, create another pipe etc... my intention was only to change the hydraulic seal mounted in the front seat (it is not present in the drawing) so that it can work in both ways. (positive pressure and '' negative pressure'')
Now I'll try to confront some pneuamatics supplier.

 

[welcome to the machine]

How did it end? I also care for myself because I have to carry back in a controlled way a sort of telescopic cylinder with multiple parades consisting of 4 concentric rods. I have no room to create the opposite room to have the double effect return. In reality I tried but the space between the inside of a barrel and the outside of the smaller one to it concentric is very little, 2-3 on a diameter of 60 mm, and therefore the useful surface is too little to have enough force in the return stroke. the vacuum could be a solution, although adjusting speed doesn't seem easy. "progressive"?

 

[antonio_sc]

I don't think I understand well, but if you have little thrust surface in the return phase you could decide to "shape" the stem so as to take advantage of the remaining part of diameter.. to tell you a little time ago I saw adopt our customer this solution (and I think they had your same problem):
https://advancedfluidpowerinc.com/wp-content/uploads/2016/03/telescopic-cylinder-image-website.gifthere are some contraindications (to the eye the stem weakens and the tube is dragged by the stem also the processing of the stem I see it "laborious". . .

 

[welcome to the machine]

Thank you. That sounds good. I have to get the air in the air because the rod, slipping, enters a hole and I would not have room for the pipes, but it should be an advantage, at least for the air in the extension. for the return I could enter from the outside of the first ring. I try and see if it moves well.

 

[New Rider]

How did it end? I also care for myself because I have to carry back in a controlled way a sort of telescopic cylinder with multiple parades consisting of 4 concentric rods. I have no room to create the opposite room to have the double effect return. In reality I tried but the space between the inside of a barrel and the outside of the smaller one to it concentric is very little, 2-3 on a diameter of 60 mm, and therefore the useful surface is too little to have enough force in the return stroke. the vacuum could be a solution, although adjusting speed doesn't seem easy. "progressive"?

It ended up that I changed work.... sin because there was a lot to do and improve. they preferred to let me go to other roads.

 

[welcome to the machine]

Then good luck!

 

[leonardo dramisino]

Good morning to all, I am new to this forum.
I'm making an agricultural machine, with a hydropneumatic leverage system.
I am unexperienced with dynamic oil, and I wanted to know if the inclination of the martinetti can improve the performance of cinematism, and why .

 

[meccanicamg]

If you put hammers in areas where you have unfavorable arms, don't help the system. You don't need to be experienced.
do not realize action lines where you move from the reversal center otherwise the system will be unstable.
is independent of the type of actuator.

 

[bip]

the more you put the cylinder perpendicular to the rotation arm, the more you can have precise control over the force.

then playing with the corner you can have a more or less progressive effect of the hydraulic cylinder. playing with the volumes of the pneumatic accumulator you can decide the "k" of the hydraulic spring.